Orbital coupling and superconductivity in the iron pnictides

TL;DR

This paper shows that strong inter-orbital interactions driven by magnetic fluctuations can induce high-temperature superconductivity in iron pnictides, with an $s^{ ext{±}}$ pairing state around 80K.

Contribution

It reveals the importance of inter-orbital pair-hopping interactions and demonstrates a self-consistent FLEX calculation predicting high $T_c$ in iron pnictides.

Findings

Superconductivity driven by magnetic fluctuations and inter-orbital interactions.

Identification of an $s^{ ext{±}}$ pairing state with $T_c$ around 80K.

FLEX calculations confirm the role of orbital coupling in high-temperature superconductivity.

Abstract

We demonstrate that strong inter-orbital interaction is very efficient to achieve superconductivity due to magnetic fluctuations in the iron pnictides. Fermi surface states that are coupled by the antiferromagnetic wave vector are often of different orbital nature, causing pair-hopping interactions between distinct Fe-3d orbitals to become important. Performing a self-consistent FLEX calculation below $T_{c}$ we determine the superconducting order parameter as function of intra- and inter-orbital couplings. We find an $s^{\pm}$-pairing state with $T_{c}\simeq80\mathrm{K}$ for realistic parameters.